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Date: Thu, 5 Jun 2008 16:14:47 -0700 (PDT)
From: "dhruba borthakur (JIRA)" <jira@apache.org>
To: core-dev@hadoop.apache.org
Subject: [jira] Commented: (HADOOP-3503) Race condition when client and
 namenode start block recovery simultaneously
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    [ https://issues.apache.org/jira/browse/HADOOP-3503?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12602843#action_12602843 ] 

dhruba borthakur commented on HADOOP-3503:
------------------------------------------

This LOG calls occur only when the lease is recovered. This shud not happen too frequently. I would like to have some log messages to debug this code when it it occurs. Do you see a LOG message that occurs outside of lease recovery?

> Race condition when client and namenode start block recovery simultaneously
> ---------------------------------------------------------------------------
>
>                 Key: HADOOP-3503
>                 URL: https://issues.apache.org/jira/browse/HADOOP-3503
>             Project: Hadoop Core
>          Issue Type: Bug
>          Components: dfs
>    Affects Versions: 0.18.0
>            Reporter: dhruba borthakur
>            Assignee: dhruba borthakur
>         Attachments: pingPong.patch
>
>
> When a client detects a error while writing to a block, it starts the generation-stamp-protocol to remove stale replicas. At the same time, if the namenode experiences a lease expiry event for that file, the namenode starts the generation-stamp-protocol for the same block. Now, the client and thr namenode ping-pongs trying to stamp the block replicas. This ping-pong can continue for a long time.

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